Girl smokers 'facing breast cancer risk'

A major study has revealed for the first time that young females taking up the habit may trigger changes in developing breast tissue which could lead to thousands more cases of the potentially fatal disease.

Researchers estimate that girls who smoke cigarettes within five years of starting their periods are 70 per cent more likely to develop the cancer.

The lifetime risk of a woman in Britain suffering breast cancer is one in nine - with most of the 39,000 cases each year coming after the menopause.

The risk is much lower for younger women, but smoking could increase the threat, it is claimed. Researchers say that in developed countries it might account for an additional 1,000 pre-menopausal breast cancer cases out of 100,000 teenage smokers.

The latest study was carried out by Dr Pierre Band and colleagues from British Columbia Cancer Agency in Vancouver, Canada.

They compared more than 2,000 women - with and without breast cancer - in terms of their history of smoking and took into account risk factors known to be linked to the disease, including hormone replacement therapy.

Women who started smoking within five years of the onset of menstruation were 70 per cent more likely to develop breast cancer than non-smokers, the study found.

There was a similar increased risk discovered in childless women who smoked 20 cigarettes a day for more than 20 years, says a report in The Lancet medical journal. Researchers found a surprising reduction in risk among women who took up smoking after the birth of their first child, but pointed out that this group was very small.

Dr Band said the findings were backed up by experimental data showing breast tissue in young women and girls was potentially more at risk from cancer- causing agents in the environment than in older females.

Breast tissue did not complete its cycle of development until after a first pregnancy, so would be particularly vulnerable to changes between puberty and the early twenties.

Dr Band added: 'These results suggest that human breast tissue is most sensitive to environmental carcinogens during periods of rapid cell proliferation when differentiation is incomplete - in puberty - and when it is never achieved in childless women.'

Previous research into a link between smoking and breast cancer had been 'inconclusive,' but the new findings would have 'public health consequences'.

A pattern emerged in the mid-1980s of more girls smoking than boys. Altogether, 26 per cent of girls aged 15 are regular smokers compared to 21 per cent of boys.

Amanda Sandford, of the antismoking group ASH, said: 'If further research confirms smoking in your teens has a special risk attached it's very important. The numbers affected could be staggering.'

Dr Stephen Duffy, of Cancer Research UK, said: 'This study suggests an increased risk of breast cancer for women who smoke in their teens and a decreased risk for those who take up smoking later in life, after their first pregnancy.

'Both of these could be chance findings since the study is relatively small.

'The picture remains confusing, and we need further research to clarify the effects of smoking on breast cancer risk.'